Formaldehyde is an easily reacting gas which is toxic and which can cause allergic reactions to people coming into contact with articles containing such gas. It is well known that formaldehyde can be used as a disinfectant for different fields of use. Furthermore, formaldehyde is gaseous at room temperature, but is easily soluble in water, therefore in practice formalin is used which is a solution of about 40% formaldehyde in water. Rather recently, methods have been devised in which sterilization with formaldehyde was made possible. Sterilization in autoclaves with the use of steam is an old, well known method, but articles treated in the autoclave with steam are subject to temperatures of about 110.degree. to 140.degree. C. It has been observed that many articles to be sterilized do not tolerate treatment at so high a temperature and thus other methods and means for sterilization have been sought. Thus, autoclaves using formalin have been suggested. Theoretically, in an autoclave using formalin, sterile articles can be obtained by treatment to about 80.degree. C. However, in practice it has been noted that although sterile items are obtained, at the same time formaldehyde residues and a layer of paraformaldehyde will settle on the articles. The quantity of such residues on the sterilized items varies in accordance with different treatments. Consequently, the use of formalin results in the aforementioned drawback, and also this is an indication that this method is not ideal.
As mentioned hereinbefore, the solution of 40% formaldehyde in water can be used, however it is an object of this invention to improve this known method by which 16 ml. of such solution is used per hundred 1. of autoclave volume. The foregoing method has yielded good results and sterilization has been obtained within a temperature range of 60.degree.-80.degree. C., but surprisingly the articles have not been free of residues.
The above disadvantage can be avoided by utilizing the present invention in which in each sterilization process a given small quantity of formalin is supplied to a vaporizer which has a liquid trap and in which the formalin is transformed into water vapor and formaldehyde which is supplied to the autoclave chamber by way of a vapor conduit.
Thus, the present method relates to a process for transforming formalin into formaldehyde and steam prior to the introduction into the autoclave chamber so that no residues of paraformaldehyde remain in the vaporizer or in the conduit connecting the vaporizer with the autoclave chamber.